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Some background info, I decided against a roof rack to transport my bikes. I searched high and low for a hitch solution only to find out there is none available. I set out to make one of my own, one that didn't look phallic, one that is completely hidden with the rear valance in place, and one that accepts any standard 1-1/4" hitch accessory. The following pictorial goes from my research all the way to an almost final product.

The rear valance was removed and I did a mock-up of the 1-1/4" receiver tube



Another angle of the receiver tube mocked-up



According to my measurements, if this receiver tube is to hide behind the rear valance and also not interfere with the battery compartment, I will need to trim the tube. Above is the chassis rail that this hitch will be bolted onto



To those who have looked under the M5 you are familiar with the muffler isolators and how they bolt to the chassis. I will utilize one on each side to provide additional strength to the hitch by distributing load. The thickness of the steel I'm using is 3/16", a little over 4mm. It is plenty strong, but I am using these additional mount points so the chassis beam won't deform from heavy tongue weight. A little over-engineering isn't bad, and the weight penalty is negligible.



I spent an evening drawing up scale plans and a Saturday afternoon cutting up some metal stock. Here are some of the pieces mocked up



I am embarrassed by my welds, but please know this is only my "prototype." I once had a Miller Dynasty 200DX TIG welder until I sold it. I put this together using a 100W flux core MIG welder. The welds are just as strong, just not as pretty. The assembly deceivingly looks large but keep in mind those are 12" ceramic tiles. The hitch is 21 inches wide (a little over 53cm). Actual weight of the entire assembly is 4.4lbs! (2.0kg). This weight does not include the set of bolts, nuts, and washers I will be using to secure the hitch to the chassis. I can lose this weight from my gut.



Another view upside down with a celebratory beverage to use as a size reference



Closeup of my fancy pants triangulation to provide superior rigidity. The pathetic weld beads is a reminder of better times when I had an awesome TIG welder.



Backside



I will be painting it tomorrow and then removing the rear bumper cover so I can drill holes into the chassis for installation. I'll be using 4 long bolts and large washers along the width of it to secure the hitch, the back end will utilize the factory studs & nuts of the muffler isolator mounts. I have the choice between ordering the OEM valance that's designed for the hitch application with the removable cutout or opting to cut the square out myself and using a plug.

This is what I plan on pulling



It folds up neatly, like so. Coincidentally my wife and I also own a Sequioa. Sometimes I ask trade cars with my wife for the weekend but she says she's scared to drive the M5.



:M5launch:
 

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Wow, nice job... I have an M5 as well and need a similar unit for mine. I was looking at the German hitch but it's for the 540 I believe. I'm eager to see how this ends up looking when you are done. I'm local (in WA state as well) and if you finish it up and it looks good, I may be interested in paying you to make one for me if you are interested.

Jennifer
 

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I have the choice between ordering the OEM valance that's designed for the hitch application with the removable cutout or opting to cut the square out myself and using a plug.


:M5launch:
Get the factory valance. Not expensive, just have it painted to match. It will be a much more finished look, unless you are very good at the cutout.
Regards,
Jerry
 

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I just so happen to have the rear trim piece that has the cutout for a hitch! I don't have the insert that goes with it though. It's painted jet black right now, but it's brand new, never installed. Might you be interested?

Jay
 

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Discussion Starter #6
I just so happen to have the rear trim piece that has the cutout for a hitch! I don't have the insert that goes with it though. It's painted jet black right now, but it's brand new, never installed. Might you be interested?

Jay
Heck yeah I'd be interested! I can order the cutout piece separate. Jet black valance on Alpine White might be interesting. PM me for details.

I've decided once I've confirmed fitment, I can make a few of these for those who would like one. I'd hate for someone to have to buy a secondary vehicle when the job can be done using an M5
 

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I can't PM just yet as I'm a "noob", but if you would, email me at [email protected] and we'll work something out!

And I was just thinking, black might be pretty badass w/ the alpine white!
 

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I think you'd have a few takers. I found a hitch on a website in the UK, but the shipping is more than the hitch, so I haven't gotten it.
 

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Here are the pictures of their product (made by Witter) complete and some bits of the installation on my M5...

We've got the entire kit laid out on a sheet - the semicircular bits are the sections that replace the bumper (fender) shock absorbers in the chassis rails and the towbar itself plugs in to the cylinder on the main beam.

The next picture probably sows the whole thing installed inside the bumper beam prior to reassembly, and the last one shows the bumper rail with the new valence attached prior to angle grinding a section out to allow the towbar to clear the beam...

SB
 

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Witter the same as the Westfalia? That's the infamous penis hitch
Hilarious!

Looks like the factory setup since the hitch has to get "inserted" from the bottom, facing up.....:grinyes:
Regards,
Jerry
 

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Witter was the one I found. The price for the hitch wasn't that outrageous, but the $250 shipping cost was...
 

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Very slick. Looking forward to seeing the results. Although I know the roof mount is the most stable, I resisted for a while. Tried the BDI rack (the one that mounts to the plate holes) with disastrous results (not to the car, but a failure of the only trunk strap sent two bikes to the pavement). Now running the Thule 753 setup, but a beefy hitch mount would be a great solution.
 

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Discussion Starter #16
An update, I mounted up my prototype, location of receiver tube couldn't be better!

The aforementioned muffler support stud at the rightmost


Hitch bolted to chassis


Inspect tube placement ...


This will have no interference with rear valance






There was a bit of deflecton when tongue weight was added, so expect an addition to the existing design. Either that or copy the bumper reinforcement mounting method per the Penis Hitch. I'm after whatever will work safely and reliably. A final hitch will be slightly heavier than the 4.x lbs I claimed for the prototype because I plan on adding material to achieve superior stiffness. Note that the receiver tube is completely concealed with the valance for the ultimate in stealthy utility. If anyone is interested, I plan on making a small batch.
 

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I think this is actually a better setup than the factory one!!
Regards,
Jerry
 

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Any updates?

Too often we see the start of these projects that give a glimmer of hope and then they fade..

Did you modify to attach like the Witter kit? If you aren't going to, I would be interested in getting the plans from you and possibly modifying them to include the bumper bracket mount. I have a guy here in Atlanta who could probably make them for a handful of us. I wouldn't be looking to really make money, just get one made and help the rest of us.

Otherwise, I may look into a group buy in Europe for the Witter and ship them over on a palette or via container.

If you are interested in buying a hitch for the E39/M5, respond here.
 
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